Field
Embodiments of the invention relate to the field of surgical instruments; and more specifically, to surgical instruments intended for use in minimally invasive surgeries.
Background
Minimally invasive surgery (MIS) (e.g., endoscopy, laparoscopy, thoracoscopy, cystoscopy, and the like) allows a patient to be operated upon through small incisions by using elongated surgical instruments introduced to an internal surgical site. Generally, a cannula is inserted through the incision to provide an access port for the surgical instruments. The surgical site often comprises a body cavity, such as the patient's abdomen. The body cavity may optionally be distended using a clear fluid such as an insufflation gas. In traditional minimally invasive surgery, the surgeon manipulates the tissues by using hand-actuated end effectors of the elongated surgical instruments while viewing the surgical site on a video monitor. Access to the surgical site may also be via a natural body orifice.
The elongated surgical instruments will generally have an end effector in the form of a surgical tool such as a forceps, a scissors, a clamp, a clip applicator, a needle grasper, or the like at one end of an elongate tube. An actuator that provides the actuating forces to control the end effector is coupled to the other end of the elongate tube. A means of coupling the actuator forces to the end effector runs through the elongate tube. To minimize the size of incision needed for the instrument access port, the elongate tube is generally of a small diameter, in some implementions about 6 millimeters or less, although larger and more complex end effectors (e.g., vessel sealers, surgical staplers, and the like) may require larger diameters, such as 10 or 13 mm. Thus, it is necessary that the means of coupling the actuator forces to the end effector be compact.
It may be desirable that the elongate tube be somewhat flexible to allow the surgical instrument to adapt to the geometry of the surgical access path. In some cases, the elongate tube may be articulated to provide access to a surgical site that is not directly in line with the surgical access port. Articulated surgical instruments may be used for single port surgery in which multiple surgical instruments are inserted through a single cannula. Single port surgery requires that the elongate tube be of a particularly small diameter and that it be capable of being articulated (either actively or passively) after passing through the cannula.
It may be desirable to use wires as the means of coupling the actuator forces to the end effector because of the flexibility they provide and because of the ability of a wire to transmit a significant force, a substantial distance, through a small cross-section. When a wire is used to transmit the actuating forces it is often necessary to provide a mechanical arrangement to translate the push-pull motion of the wire to an open-close motion of an end effector. The small size of the end effector and the unique requirements for surgical instruments significantly increases the difficulty of providing a reliable mechanical arrangement.
In view of the above, it would be desirable to provide an improved apparatus and method for translating a push-pull motion to an open-close motion of a surgical end effector of a surgical instrument intended for use in minimally invasive surgeries with increased reliability.